'\" et
.TH dirent.h "0P" 2017 "IEEE/The Open Group" "POSIX Programmer's Manual"
.\"
.SH PROLOG
This manual page is part of the POSIX Programmer's Manual.
The Linux implementation of this interface may differ (consult
the corresponding Linux manual page for details of Linux behavior),
or the interface may not be implemented on Linux.
.\"
.SH NAME
dirent.h
\(em format of directory entries
.SH SYNOPSIS
.LP
.nf
#include <dirent.h>
.fi
.SH DESCRIPTION
The internal format of directories is unspecified.
.P
The
.IR <dirent.h> 
header shall define the following type:
.IP "\fBDIR\fR" 8
A type representing a directory stream. The
.BR DIR
type may be an incomplete type.
.P
It shall also define the structure
.BR dirent
which shall include the following members:
.sp
.RS 4
.nf

ino_t  d_ino       \fRFile serial number.\fR
char   d_name[]    \fRFilename string of entry.\fR
.fi
.P
.RE
.P
The
.IR <dirent.h> 
header shall define the
.BR ino_t
type as described in
.IR <sys/types.h> .
.P
The array
.IR d_name
is of unspecified size, but shall contain a filename of at most
{NAME_MAX}
bytes followed by a terminating null byte.
.P
The following shall be declared as functions and may also be defined as
macros. Function prototypes shall be provided.
.sp
.RS 4
.nf

int            alphasort(const struct dirent **, const struct dirent **);
int            closedir(DIR *);
int            dirfd(DIR *);
DIR           *fdopendir(int);
DIR           *opendir(const char *);
struct dirent *readdir(DIR *);
int            readdir_r(DIR *restrict, struct dirent *restrict,
                   struct dirent **restrict);
void           rewinddir(DIR *);
int            scandir(const char *, struct dirent ***,
                   int (*)(const struct dirent *),
                   int (*)(const struct dirent **,
                   const struct dirent **));
void           seekdir(DIR *, long);
long           telldir(DIR *);
.fi
.P
.RE
.LP
.IR "The following sections are informative."
.SH "APPLICATION USAGE"
None.
.SH RATIONALE
Information similar to that in the
.IR <dirent.h> 
header is contained in a file
.IR <sys/dir.h> 
in 4.2 BSD and 4.3 BSD. The equivalent in these implementations of
.BR "struct dirent"
from this volume of POSIX.1\(hy2017 is
.BR "struct direct" .
The filename was changed because the name
.IR <sys/dir.h> 
was also used in earlier implementations to refer to definitions
related to the older access method; this produced name conflicts. The
name of the structure was changed because this volume of POSIX.1\(hy2017 does not completely
define what is in the structure, so it could be different on some
implementations from
.BR "struct direct" .
.P
The name of an array of
.BR char
of an unspecified size should not be used as an lvalue. Use of:
.sp
.RS 4
.nf

sizeof(d_name)
.fi
.P
.RE
.P
is incorrect; use:
.sp
.RS 4
.nf

strlen(d_name)
.fi
.P
.RE
.P
instead.
.P
The array of
.BR char
.IR d_name
is not a fixed size. Implementations may need to declare
.BR "struct dirent"
with an array size for
.IR d_name
of 1, but the actual number of bytes provided matches (or only slightly
exceeds) the length of the filename string.
.SH "FUTURE DIRECTIONS"
None.
.SH "SEE ALSO"
.IR "\fB<sys_types.h>\fP"
.P
The System Interfaces volume of POSIX.1\(hy2017,
.IR "\fIalphasort\fR\^(\|)",
.IR "\fIclosedir\fR\^(\|)",
.IR "\fIdirfd\fR\^(\|)",
.IR "\fIfdopendir\fR\^(\|)",
.IR "\fIreaddir\fR\^(\|)",
.IR "\fIrewinddir\fR\^(\|)",
.IR "\fIseekdir\fR\^(\|)",
.IR "\fItelldir\fR\^(\|)"
.\"
.SH COPYRIGHT
Portions of this text are reprinted and reproduced in electronic form
from IEEE Std 1003.1-2017, Standard for Information Technology
-- Portable Operating System Interface (POSIX), The Open Group Base
Specifications Issue 7, 2018 Edition,
Copyright (C) 2018 by the Institute of
Electrical and Electronics Engineers, Inc and The Open Group.
In the event of any discrepancy between this version and the original IEEE and
The Open Group Standard, the original IEEE and The Open Group Standard
is the referee document. The original Standard can be obtained online at
http://www.opengroup.org/unix/online.html .
.PP
Any typographical or formatting errors that appear
in this page are most likely
to have been introduced during the conversion of the source files to
man page format. To report such errors, see
https://www.kernel.org/doc/man-pages/reporting_bugs.html .
